DE4134871C2 - Post system and method for restoring or stabilizing teeth - Google Patents

Description

The invention relates to a pen system and a method for restoration or stabilization of teeth according to the preamble of claims 1 and 11 (DE 38 25 601 A1).

State of the art

The retention areas of the natural tooth structure are sufficient for the restoration of deeply destroyed teeth in most cases not out. Conditionable enamel, as a prerequisite for adhesive cemented composite abutments usually hardly available. A building material with sufficient adhesion to possibly conditioned Dentin surfaces are not yet available.

To increase retention, core structures anchored with pins are generally incorporated and then crowned.

The different pin systems can either be in the root canal (intracanalicular) or in the peripheral Dentin (parapular) to be anchored.

Parapulpary screws or pins are relatively short and cause a small diameter relatively little increase in retention. The danger of perforations in the area of the inner (Pulp) or external soft tissue (periodontal) is large (thin peripheral dentin coat, difficult intraoral handling). In addition, the necessary preparation measures and / or through the incorporation of the pins or screws (micro) cracks in the tooth structure can be induced (→ structural damage, loss of stability, leakage).  

In most cases, endodontic treatment, e.g. B. in the sense of processing and Bacteria-tight filling of the root canals (or the root canal) required or already carried out, so that intracanalicular anchored pen structures offer themselves.

By preparing an access cavity and standardized preparation of the root canal, the During an endodontic treatment, natural tooth structure is removed, which leads to destabilization root-treated teeth. In addition, it comes from removing the vital pulp very likely to cause lasting changes in dentin quality, which is a cause increasing brittleness of the residual tooth substance.

Retention mechanisms of previous pen assembly systems

1.Thread (with and without fastening cement)
2. Friction fit + fastening cement

The core abutments are either modeled with a plastic filling material in the mouth and anchored to the mechanical retention aids of the screw head or individually in form cast pen assemblies made in one piece (pen + assembly) in the laboratory.

Such a pen assembly system is for example from DE 38 25 601 A1 known. This consists of a fiber-reinforced Plastic-made root canal, which is processed into a Root canal introduced and with the help of a hardenable Fixing plastic, so-called dentine adhesive, fixed becomes. The adhesion of the root post created by such dentine adhesives is of poor quality. In particular subject to them during a phase change in the course of solidifying a Volume shrinkage, which leads to detachment of the fastening plastic leads from the dentin wall.

DE 39 01 640 A1 also shows a generic pen assembly system. In contrast to the present one, however, Invention can be easily removed from the tooth without there is substantial damage. For this, a special fiber-reinforced composite material proposed.

Finally, DE 40 11 568 A1 shows a root canal filling device with a flexible, plastically deformable filler pen, which is inserted into a root canal and there changed in shape by injection of a filler is that the root canal volume by expanding the Pin is closed. A constructive pen structure in The present invention is based on the flexibility of the aforementioned filler pen not possible.

Further disadvantages of the known systems result from the following Enumeration:

Disadvantages of the previous pen assembly systems 1. Bond-dentin composite (root canal)

The above Adhesive mechanisms do not result in a force-locking connection of the pin or screw to the surrounding dentin. A stabilization of the weakened by the endotontic treatment Hard tooth substance does not take place. The gap between the pencil and dentin surface cannot bacteria-proof.

2. Shape and dimension of the intracanalicular pin segment

The above Adhesive components are based on the conformity of shape between the standardized pins and the root canal and therefore require the preparation of a "pin cavity". With a few exceptions, the root and root canal cross-sections give way to the permanent ones Teeth from the circular shape, only a few roots or root canals run straight. Oval or curved root canals can e.g. T. are insufficiently prepared, d. H. of the The pen structure receives little retention. At the same time, there is a risk of root perforation. The preparation of an approximately round "pencil cavity" results in extensive healthy dentine removed, with the result of a z. T. massive destabilization of the already weakened or brittle Hard tooth substance. Inadequate shape congruence between the pin and the duct lumen can also lead to reinfections of the root canal (e.g. via side canals). The conical shape results in horizontally running friction pins Force vectors that may lead to blasting, partial fractures or fractures of the roots can. Tensions in the area of the thread pitch and poor drainage options for the fixing cement when repositioning the pins can further increase this danger.  

The specifications for dimensioning (length / diameter) of the conventional root canal pins or screws are derived from the composite mechanisms mentioned and the shape of the channel lumen or the "pen cavity". Relatively long pins or pins are generally used for secure retention Screws are recommended, which often extend to the apical third of the canal and with a z. T. considerable loss of healthy tooth structure. A bacteria-proof closure of the The canal lumen can often not be guaranteed due to the root filling remaining in the apical third of the canal will.

3. Material

The indication-specific property profile of root posts or screws (bending stress) essentially requires rigid-elastic, ductile materials with sufficient tensile and Shear strength parameters. Depending on the metal alloys used so far, of the individually different, physico-chemical environment in the root canal systems to be supplied, the following disadvantages:

• - Corrosion of the pins in the root canal.
• - Discoloration of the hard tooth substance due to corrosion products.
• - Discoloration of the tooth structure due to the inherent color and opacity of the metal pins, in particular in the area of the tooth neck and for metal-free superstructures.
• - Galvanic element formation (superstructure).

4. clinical handling

The common systems are available in the form of a set, the necessary instruments (e.g. drill) is generally matched to the prefabricated pins. Nevertheless, the preparation of the pen cavity is often problematic and z. T. extremely time consuming. Overall, the techniques are cumbersome and time and cost intensive.

5. individually cast superstructures

A sufficiently accurate impression of the deep pen cavities is extremely difficult, castable Pens can only be used in rare cases. In addition, the individual production of a cast pen structure requires at least two treatment sessions on the patient and is accordingly time-consuming and costly.

The indication for the incorporation of parapulpary or intracanalicular pins is today generally narrow and is limited to those cases that do not have sufficient retention Have anchoring of a superstructure.

The invention aims to stabilize the endotontic treatment weakened tooth structure.

The invention achieves this aim by the subject matter of claim 1 and by the method of claim 12. Further embodiments of the invention are in subclaims 2 to 11 as well 13 to 15.  

Advantages of the invention

An idea according to the invention is based on retention or stabilization pins of a hollow, defined in the center, perforated, in its physical, mechanical, biological and chemical properties suitable pen, with direct and / or Indirectly attached application device for plastic filling or fastening materials.

The actual core structure can be made in one piece with the pin or in a suitable manner be put together with this.

Another option is to close the upper end of the pin in the sense of a retention head design and model the core structure from plastic materials in the mouth and to the to attach the intended retentions.

1. Bond to dentin

The plastic filling or fastening material is based on the maximum attainable adhesive values selected on possibly conditioned dentin surfaces. Other criteria are the earmarked Processing and the possibility of application using the system provided. The adhesive values of the filler material on the pen surface should match the values on the dentine interfaces correspond, if necessary, the surface of the intended pins is suitably coated. In principle, those plastic filling or fastening materials are preferred which experience a relatively low shrinkage during curing, u. U. can be elastic Coating the pen compensates for the shrinkage of the filler.

The proposed system enables a non-positive connection between the hard tooth substance (Root canal dentin) and a pen. So the basics of a "composite construction" fulfilled, with the consequence of a stabilization of the residual tooth substance. The preparation of a pencil cavity and the associated weakening of the tooth can to be largely dispensed with; in most cases z. B. the removal of the root filling from the upper root canal sections. The frictional connection between the corresponding dentin and post surfaces also ensures a tight seal of the joint gap.

2. Shape and dimension

Thanks to the non-positive connection and the safe application of the plastic filling or Fastening material can largely be dispensed with the preparation of a pen cavity. Shape mismatches between pin and channel lumen are completely filled. The shape and diameter of the pins are based on the geometry of the preparation of the root canal (in the course of root filling) last used instruments that are specified in Standards are generally available.

The length of the pins depends on the length of the later superstructure and its occlusal stress. Other factors are the degree of destruction, and any other existing ones Retention options and the intended number of pins per tooth. Due to the positive connection to the tooth structure, "adhesive" pins can be essential be chosen shorter than comparable, cemented and / or screwed pin systems.  

4. Material

The specific requirement profile for "adhesive" pens is essentially determined by the required Tensile and shear strength parameters defined. Non-metallic pens, such as reinforced plastic or ceramic pens, which may can be combined with each other and / or with metal parts, point to pure Metal pens have a number of advantages:

• - corrosion resistance.
• - Aesthetically demanding restoration, avoiding direct and / or indirect (by irradiation of a foreign color) discoloration of the hard tooth substance.
• - Electrically neutral.
• - Chemically compatible with the plastic composite materials (filling and / or construction material); e.g. T. direct chemical bond.
• - Adjustable material properties, e.g. B. by suitable doping or amplification mechanisms.

5. Advantages in handling

• - The preparation of a pen cavity is not necessary.
  This virtually eliminates the risk of root perforation when inserting a post and significantly shortens the treatment time required.
• - The pen can easily be fitted in and safely repositioned under visual control.
• - The filling material is only applied after the final positioning has been checked.
• - Due to the defined design of the longitudinal and transverse holes, a directed flow of the Filler material; Drainage channels prevent an uncontrolled increase in pressure and ensure a homogeneous distribution of the filling material in the joint gap.
• - The integrated, bacteria-proof root filling is only removed in the upper part of the canal.
• - Uniform wetting of the joint gap with filling or fastening material.
• - A predetermined breaking point allows easy removal of the application device.
• - Reproducible properties of the plastic filling or fastening material mechanical mixing.

Further advantages and refinements of the invention result from the following description of preferred exemplary embodiments. In the description, the attached schematic drawing referred. The drawing shows:

FIG. 1 shows a pin according to the invention with attached applicator device for plastic filler material;

Figure 2 shows a further pin according to the invention with attached core structure and an attached application device for plastic filler material.

Fig. 3 with an inserted application device, fitted to the pin of Figure 1 into a root canal. and

Fig. 4 shows an inventive pin system after attaching the pin in the root canal with a plastic core structure.

Description of the preferred embodiments ( FIGS. 1 to 4)

The exemplary embodiments described show some possibilities for realizing the invention Basic idea, although this is of course not limited to these examples but includes all other possibilities that realize the basic idea.

The principle on which the application is based naturally applies to the broadest extent to all packing elements Senses (e.g. root filling pins, parapular pins etc.), which e.g. B. to supply "stretched" Cavities are suitable.

The device is based on suitable pins 14 with attached application device 2 , which directly with the pin z. B. connected via a predetermined breaking point 1 or indirectly z. B. can be plugged through a cannula-like extension.

The pins 14 are preferably hollow, at least in part, and have a longitudinal bore 12 in the exemplary embodiment described. In addition, the pins 14 can contain various perforations 13 , for example in the sense of cross bores. The surface 21 of the pins 14 can contain various drainage or distribution grooves 22 for the plastic filling or fastening material 3 + 5 . These can basically run parallel and / or transverse to the longitudinal axis of the pin and / or circular z. B. arranged spirally. To optimize the bond with the plastic filling or fastening material 3 + 5 , the surface 21 of the pins 14 can additionally be coated in a suitable form.

The upper end of the pin 14 may e.g. B. have different mechanical retentions 11 or be connected to a prefabricated core structure 15 . The assembled core structure 15 can either be made in one piece with the pin 14 or indirectly, for. B. are attached using suitable fasteners. The surface 16 of the prefabricated core structure 15 can, for. B. have suitable mechanical retentions and / or be coated as desired and is thus manual corrections z. B. accessible by individual application of composite.

The pins 14 are to be produced in a suitable shape and size, it being advisable for practical reasons to orientate themselves to the standard values of the root canal instruments or root canal filling pins. The size ratio of pen / application device is essentially determined by the handling and the required volume of plastic filling material 3 and 5 .

The application device 2 can be designed, for example, and essentially contains a suitable plastic filling or fastening material 3 and 5 . The 1st component of the filling material 3 is from the 2nd component 5 z. B. separated by a membrane 4 . By means of a suitable stamp 6 , the membrane 4 can be pressure z. B. destroy the material component 5 , which causes an activation of the two components 3 + 5 .

The geometric shape, composition and arrangement of the capsule, filler components, membrane and stamp can be varied as desired. The corrugation 8 of the handle proposed for better handling can also be designed as desired. Theoretically, single-phase filling or fastening materials can also be used. B. autopolymerizing, initialized by light or harden in a similar manner. Furthermore, a plastic filling material activated and mixed outside the filling device would be conceivable, which is filled into a suitable application system after it has risen. However, this process technology has various disadvantages, such as. B. possibly entrapped air, contamination and cumbersome handling.

The formal design of the application system could e.g. B. by suitable holding devices 7 a direct introduction both in any mechanical mixing device, as well as in a suitable filling aid 9 z. B. facilitate with a movable pin 10 . The filling aid 9 could, for. B. be designed in the form of pliers with a defined ratio of forces (process-specific limitation of the pressure achievable in the pen). The shape, appearance, size and arrangement of the holding device 7 , the filling aid 9 and the bolt 10 which may be required serve exclusively to implement the basic idea of the invention and can therefore be designed to be suitable for any purpose. For example, other mechanical, pneumatic or hydraulic auxiliary devices can also be used.

The material properties of a suitable plastic filling material should be matched to the application-specific requirements. In particular, sufficient tensile and shear strength values should be guaranteed and fatigue should be largely excluded. The biological and chemical properties should allow processing in the oral environment. In addition, the adhesion potential of the pin surface 21 for the filling material 3 + 5 used should correspond to that of the possibly conditioned dentin interfaces in the root canal.

After a suitable preparation of a pen cavity, e.g. B. in the sense of removing an already inserted root filling 18 in the upper root canal sections, the side walls of the pin canal are cleaned and, if necessary, conditioned. The pens are e.g. B. selected according to the size of the treatment instrument last used in the course of the root filling 18 , fitted and possibly checked by X-ray. After removal from the mouth, the activation and homogeneous mixing of the plastic filling material 3 + 5 = 20 follows. The pen is inserted into the pen channel with the application device 2 and filling aid 9 attached. (The filling aid device can also be placed on the application device after inserting the pen).

By pressing the stamp 6 , the plastic material 20 can be injected into the pen without bubbles. By suitable design of z. B. transversely and or parallel obliquely to the longitudinal axis of the pin arranged holes, the material can be optimally pressed out and fills the joint between pin and channel wall homogeneously and bubble-free; the air is forced upwards. Distribution grooves 22 on the pin surface 21 , e.g. B. in the form of an incisal spiral, support the uniform wetting of the opposite interfaces and a homogeneous closure of the joint gap; the excess of plastic filling material 20 flows off incisally (control option).

Another possibility is to fill material before the final reduction of the Squeeze the pin and under, if necessary rotating, feed, with continuous filling material delivery, to reposition the pen to the end position; any combinations of those described Techniques and their addition with z. B. differently introduced material (possibly external mixed and / or separately injected) are conceivable.

When using a complete pin structure (pin 14 + core structure 15 ) z. B. directly underneath the attached core structure 15, transverse bores 13 , caused by outflowing filler material together with the excess flowing out of the canal lumen, compensate for any form mismatches between the base of the core structure and the cavity floor.

After the filling material has set or hardened, the application device can be broken off at the predetermined breaking point 1 and the pen can be shortened to the required length.

Possibly. Several channels are provided with pins, including combinations of pin systems with and without an attached core structure are conceivable.

If simple pins 14 with mechanical retentions 11 were used, the core structure 19 can be made of suitable plastic materials and individually, e.g. B. be ground to accommodate a crown. The same plastic materials are also suitable for the individual correction of core structures 15 , which are produced directly in one piece with the pins 14 .

After completing the pen assembly, an X-ray check can be carried out, if necessary Add suitable X-ray opaque fillers to the pen, structure and / or filler materials used.

The system that realizes the basic ideas is also suitable, for example, for simple, bubble-free, safe and / or compact application of e.g. B. drug deposits in the course of a root canal treatment. A suitable pen could e.g. B. for the duration of the deposit in Channel remain and, if necessary, support the complete removal of the insert; any variations are conceivable.

Furthermore, there are various root canal fillings or root canal filling techniques, for example or root filling systems on the basis of the basic ideas according to the invention described conceivable.

Claims (15)

1. pin system for the restoration or stabilization of teeth with at least one pin ( 14 ) that can be inserted into a prepared root canal and a plastic and hardenable joining material ( 3 , 5 , 20 ), characterized by a material of the pin surface and a joining material ( 3 , 5 , 20 ) such that the adhesive values of the hardened joining material ( 20 ) on the root canal wall and the opposite pin surface correspond to one another, so that a non-positive connection between the root canal wall, the hardened joining material ( 20 ) and the pin ( 14 ) is produced. 2. Pen system according to claim 1, characterized in that the root canal wall and / or the post surface are conditioned. 3. pin system according to claim 2, characterized in that the pin ( 14 ) is at least partially coated and the adhesive values of the hardened joining material ( 20 ) with respect to the coated pin surface and with respect to the root canal wall correspond approximately to each other. 4. pin system according to claim 1 to 3, characterized in that the joining material ( 3 , 5 ) is a composite material. 5. pen system according to claim 4, characterized in that the pin ( 14 ) is coated with elastic materials. 6. pen system according to one of claims 1 to 5, characterized in that the pin ( 14 ) z. B. consists of plastic or ceramic. 7. pen system according to claim 6, characterized in that the pin ( 14 ) consists of reinforced plastic or ceramic materials. 8. Pen system according to one of claims 4 to 7, characterized in that the pin ( 14 ) consists of a chemically compatible with the composite materials of the pin ( 14 ) plastic. 9. pin system according to one of the preceding claims, characterized in that the joining material ( 3 , 5 ) at least partially forms a chemical bond with the pin surface. 10. pin system according to one of the preceding claims, characterized in that the joining material ( 3 , 5 ) through a longitudinal bore ( 12 ) in the interior of the pin ( 14 ) can be introduced. 11. pin system according to claim 10, characterized by a joining material ( 3 , 5 ) which, after hardening with the material of the pin ( 14 ) also forms a composite material inside the pin ( 14 ). 12. A method for restoring or stabilizing teeth, in which at least one pin ( 14 ) and a plastic and hardenable joining material ( 3 , 5 ; 20 ) are introduced into a prepared root canal, characterized in that the material of the post surface and the joining material ( 3 , 5 ; 20 ) are selected such that the adhesive values of the hardened joining material ( 20 ) on the root canal wall and the opposite pin surface correspond to one another, so that a non-positive connection between the root canal wall, the hardened joining material ( 20 ) and the pin ( 14 ) arises. 13. The method according to claim 12, characterized in that the root canal wall and / or the pin surface is at least partially conditioned to increase the boundary surface adhesion of the joining material ( 3 , 5 ). 14. The method according to claim 12 or 13, characterized in that the pin surface is at least partially coated to increase the interfacial adhesion of the joining material ( 20 ). 15. The method according to any one of claims 12 to 14, characterized in that a joining material ( 3 , 5 ) is used, which has maximum adhesion values on the root dentin surface and the smallest possible volume shrinkage during the phase change during hardening.